Only company in the world who is authorized to work on and service the Ford GT supercar transmission

Only company in the world to achieve CARB legality when tuning a forced induction application through a factory NISSAN ECU

We Know Cars

From our sales and customer service team, who are enthusiast themselves, to our in-house research and development team to our in-house installation center we are constantly testing and developing new products and working with other industry manufacturers to improve their products. These resources allow our Customer Support teams to be the most highly experienced team around.

Racing Heritage

STILLEN's founder, Steve Millen, enjoyed a wildly successful, multi-decade racing career in which he earned several titles including:

2 time IMSA world champion

2 time Mickey Thompson off-road champion

24 hours of Le Mans class winner

24 hours of Daytona overall winner

12 hours of Sebring overall winner

Winningest driver in IMSA GT history

Today, you can find Steve within the STILLEN campus overseeing new product development, checking in on the progress of installs being done in the service shop, discussing which new vendors to offer our customers and more.

Made in the USA

We design and manufacturer all STILLEN parts in our Southern California based campus, which consists of several warehouses and manufacturing plants that span over 100,000 sq. ft. and allow us to manufacture CNC machined, fabricated tube and sheet metal, and carbon fiber products in-house. To see our capabilities for yourself, stop by for a tour the next time you're in the Southern California area!

Choose from Thousands of Parts

STILLEN manufacturers thousands of products across a variety of vehicle platforms and works with hundreds of vendors to bring you the best selection of parts for your vehicle.

Low Price Guarantee

Bring us any advertised price for a product that we carry and we'll do our best to beat it. We believe that our customers deserve the best price possible for the products they buy, so our team is dedicated to giving you the best possible deal. Always make STILLEN your last stop for maximum savings and excellent customer service.

1996-2013 Ford Mustang V8 Prolite Xact Flywheel - 8 Bolt - 14.4 lbs

Manufacturer

ACT's mission is to serve our customers in an extraordinary way with business excellence, outstanding product quality, and exceptional value which meets even the most challenging needs of our customers. ACT leads the industry in performance clutches and flywheels by manufacturing an extensive product line, including single disc clutches, twin disc clutches, carbon clutches and flywheels. Our Mission is to advance a family of people committed to innovation, measurable results and well developed systems of operation which provide adventure, quality and efficiency. Each ACT product is unparalleled in strength, durability and materials. ACT products combine all the features needed in a performance clutch or flywheel with many different combinations to choose from. Materials used from design to production provide the platform for a solid engineered part. ACT provides quality that lasts, materials that work and processes that perform to ensure calculated results. Simple yet advanced. Finite Element Analysis: ACT uses powerful Finite Element Analysis (FEA) computer software to test and evaluate products in a virtual environment. The FEA software accompanies the latest CAD and 3D solid modeling software used by ACT's research and development department so that numerous design alternatives can be considered long before coming to market with a new product. ACT's FEA software mechanical stress, heat transfer, thermal stress, vibration and buckling analysis under virtually any load condition which can help identify potential problems in a particular design. Custom Data Recording Press: ACT uses a computer operated data recording press to cycle, test and record pressure plate clamp load, working range, release load and release travel. Each pressure plate is load tested and cycled to ensure parts meet ACT's strict quality standards. This special equipment makes testing accurate, efficient, and thorough so both existing parts and prototype designs can be quickly evaluated. This equipment also allows ACT to create custom setups for customers and give them a dyno sheet for that exact assembly. Laboratory Testing: Utilizing the latest in laboratory testing, ACT continues to experiment with different friction materials and design alternatives for future product development. Friction material tests help ACT to evaluate coefficient of friction, fade, wear, and recovery under different load, speed and temperature conditions. Laboratory burst testing and material testing is performed on parts for SFI certification on a scheduled basis and regularly performed on new parts.